The present invention relates to a distributed system and method for controlling train movement in a track network.
Train movement control is a complicated activity even with computer support. The trains must be directed to the correct destinations within a tight time schedule, and the physical limitations of the track network impose substantial contraints on train movement. Obviously, two trains travelling on the same track cannot pass each other in opposite directions or in the same direction, except where sidings occur. Safety considerations limit how closely trains may approach each other and at what speeds they may travel at different points in the track network. The length of a single train and its weight and weight distribution may vary as the train travels from destination to destination. These factors affect braking distances and determination of which sidings are long enough to accommodate the train.
This activity usually is coordinated offboard the trains, and movement authority is communicated to each train by signal aspect information from wayside logic in signaled territory and by radio communications in non-signaled territory. Such coordination requires information about the location of each train. Such information can be available from estimations, from voice communications, and from track sensors. Current concepts exist to determine train positions using navigation systems such as the Global Positioning System (GPS).
GPS is an example of a current navigation system in which numerous signals are transmitted from points which are known or ascertainable by the receiver. By tracking signals from such a system, a receiver may be able to derive information such as its position, direction, or velocity. Of course, a train will follow the railroad track, but it will be useful to acquire very accurate position information from a navigation system.
Disadvantages of current train control concepts include requirements for elaborate train dispatching offices and highly detailed onboard train data bases. These undesirable requirements would dramatically increase the cost of positive train control and reduce the likelihood of eventual implementation.
For example, current concepts would require major modification or complete redesign and replacement of train dispatching office computing systems. This would be very expensive, would require additional training for dispatchers, would increase the susceptibility for the introduction of errors into the system, and would increase human stress during the transition between two dispatching office systems.
Current concepts also would require highly detailed onboard train data bases. This would create a logistics problem in maintaining an up-to-date configuration of the data base on the highly mobile trains. It also would place additional operational requirements on the system to handle non-equipped trains or trains with failed equipment.
The present invention for controlling train movement uses a distributed architecture. In one embodiment, wayside controllers receive signals from individual trains, including position information which can be derived from a navigation system. The wayside controllers interface with a central train control network and coordinate local train movement. A designated section of the track network is assigned to each wayside controller, and that controller can issue incremental movement authority to a train within that designated section of the track network.
In some embodiments, the central train control network may issue movement authority for a relatively large section of track, and a wayside controller automatically partitions that authority into increments. The wayside controller may then transmit the incremental movement authority to the train at the appropriate times. For example, an incremental movement authority might not be executed until satisfaction of a condition, or until after the elimination of any local conflicts.
In some embodiments, the designated section of the track network could be divided into blocks, and the wayside controller could contain a data base of definitions of those blocks. The incremental movement authority transmitted to a train could comprise permission to move to an end of a specific block at a speed not exceeding a specific limit.
Embodiments of the present invention of a distributed train control system can be simpler and more cost effective than the current concepts for a centralized system. The present invention can be implemented to accommodate monitored manual switches or remote powered switches, it does not require an onboard train data base, and does not require major modifications or replacement of existing dispatching office equipment. The present invention may be implemented in non-signaled territory and in signaled territory. Ambiguity for the dispatcher or for the train engineer can be minimized, since they can interact with the system in the same way, regardless of whether there is non-signaled territory movement authority (MA), centralized traffic control (CTC) in signaled territory, or automatic incremental movement authority. Operation can be as it is today for non-equipped trains or for trains with failed equipment.
The features of the present invention which are believed to be novel are set forth below with particularity in the appended claims. The invention, together with further advantages thereof, may be understood by reference to the following description in conjunction with the accompanying drawings, which illustrate specific embodiments of the invention.